Observation and experiment are the two sources of scientific knowledge. Aristotle was the father of the Greek sciences, and has made a lasting contribution to physics, astronomy, biology, meteorology and other sciences. The Greek method of acquiring scientific knowledge was mainly speculative, hence science as such could make little headway during the time of the Greeks.

The Arabs who were more realistic and practical in their approach adopted the experimental method to harness scientific knowledge. Observation and experiment formed the vehicle of their scientific pursuits, hence they gave a new outlook to science of which the world had been totally unaware. Their achievements in the field of experimental science added a golden chapter to the annals of scientific knowledge and opened a new vista for the growth of modern sciences.

Al-Ghazali was the follower of Aristotle in logic, but among Muslims, Ishraqi and Ibn-iTaimiyya were first to undertake the systematic refutation of Greek logic. Abu Bakr Razi criticized Aristotle's first figure and followed the inductive spirit which was reformulated by John Stuart Mill. Ibn-i-Hazm in his well known work Scope of Logic lays stress on sense perception as a source of knowledge and Ibn-i-Taimiyya in his Refutation of Logic proves beyond doubt that induction is the only sure form of argument, which ultimately gave birth to the method of observation and experiment.

It is absolutely wrong to assume that experimental method was formulated in Europe. Roger Bacon, who, in the west is known as the originator of experimental method in Europe, had himself received his training from the pupils of Spanish Moors, and had learnt everything from Muslim sources.

The influence of Ibn Haitham on Roger Bacon is clearly visible in his works. Europe was very slow to recognize the Islamic origin of her much advertised scientific (experimental) method. Writing in the Making of Humanity, Briffault admits,

"It was under their successors at the Oxford School that Roger Bacon learned Arabic and Arabic science. Neither Roger Bacon nor his later namesake has any title to be credited with having introduced the experimental method. Roger Bacon was no more than one of the apostles of Muslim science and method to Christian Europe; and he never wearied of declaring that the knowledge of Arabic and Arabic science was for his contemporaries the only way to true knowledge. Discussions as to who was the originator of the experimental method......are part of the colossal misrepresentation of the origins of European civilization.

The experimental method of Arabs was by Bacon's time widespread and eagerly cultivated throughout Europe. Science is the most momentous contribution of Arab civilization to the modern world, but its fruits were slow in ripening. Not until long after Moorish culture had sunk back into darkness did the giant to which it had given birth, rise in his might. It was not science only which brought Europe back to life. Other and manifold influences from the civilization of Islam communicated its first glow to European life.

For although there is not a single aspect of European growth in which the decisive influence of Islamic culture is not traceable, nowhere is it so clear and momentous as in the genesis of that power which constitutes the permanent distinctive force of the modern world, and the supreme source of its victory-natural science and the scientific spirit, The debt of our science to that of the Arabs does not consist in startling discoveries or revolutionary theories; science owes a great deal more to Arab culture, it owes its existence.

The ancient world was, as we saw, pre-scientific. The astronomy and mathematics of Greeks were a foreign importation never thoroughly acclimatized in Greek culture. The Greeks systematized, generalized and theorized, but the patient ways of investigations, the accumulation of positive knowledge, the minute methods of science, detailed and prolonged observation and experimental enquiry were altogether alien to the Greek temperament.

Only in Hellenistic Alexandria was any approach to scientific work conducted in the ancient classical world. That spirit and those methods were introduced into the European world by the Arabs."

In his outstanding work The Reconstruction of Religious Thought in Islam, Dr. M. Iqbal, the poet of Islam writes, "The first important point to note about the spirit of Muslim culture then is that for purposes of knowledge, it fixes its gaze on the concrete, the finite. It is further clear that the birth of the method of observation and experiment in Islam was due not to a compromise with Greek thought but to prolonged intellectual warfare with it. In fact the influence of Greeks who, as Briffault says, were interested chiefly in theory, not in fact, tended rather to obscure the Muslim's vision of the Quran, and for at least two centuries kept the practical Arab temperament from asserting itself and coming to its own."

Thus the experimental method introduced by the Arabs was responsible for the rapid advancement of science during the mediaeval times.